1. Field of the Invention
The present invention relates generally to a drying processing method and an apparatus using the drying processing method. More specifically, the invention relates to a drying processing method for drying an object to be treated, such as a semiconductor wafer and a glass substrate for a LCD, by allowing the object to be in contact with a dry gas, and an apparatus using the drying processing method.
2. Related Background Art
In a typical manufacturing processing in a semiconductor equipment, there has been widely used a cleaning processing method for sequentially immersing an object to be treated (hereinafter referred to as a "wafer"), such as a semiconductor wafer and a glass substrate for a LCD, in a treatment solution, such as a chemical and a rinse solution (a cleaning solution), which is stored in a processing bath. Such a cleaning processing apparatus has a drying processing apparatus for allowing a dry gas, which is of a vapor of a volatile solvent, such as IPA (isopropyl alcohol), to be in contact with the surface of the cleaned wafer to cause the dry gas to be condensed or adsorbed to remove the moisture of the wafer and dry the wafer (see Japanese Patent Laid-Open No. 8-45893).
As described in Japanese Patent Laid-Open No. 8-45893, a conventional drying processing apparatus of this type comprises: a carrier gas supply part for supplying a carrier gas, e.g., nitrogen (N.sub.2) gas; a vapor generator, which has multistage evaporating dishes for receiving a dry gas, e.g., IPA (isopropyl alcohol), and a heater; a main supply passage having a shut-off valve provided therein for supplying a vapor generated by the vapor generator, i.e., a dry gas, to a drying processing chamber; and a heater for heating the main supply passage.
According to the conventional drying processing apparatus with this construction, N.sub.2 gas is supplied from the N.sub.2 gas source to the vapor generator to be mixed with the IPA gas vaporized by the vapor generator to be supplied to the processing chamber via the main supply passage, so that the wafer housed in the processing chamber contacts the IPA gas to remove the moisture of the wafer and dry the wafer.
However, in this type of conventional drying processing apparatus, the dry gas is produced in the vapor generator having multistage evaporating dishes, so that the heat capacity of the vapor generator is limited. Thus, there is a problem in that the amount of evaporation of IPA is limited to lower the evaporative power. Therefore, there is a problem in that it takes too much time until the supply of the IPA to the vapor generator is stopped after the IPA is supplied to the vapor generator, i.e., until the generation of the IPA gas is stopped after the IPA gas is generated.
In addition, since the vapor generator has the multistage evaporating dishes, there is a problem in that the size of the whole system is large.
Moreover, when the drying processing includes a step of reducing the pressure in the processing chamber to a pressure lower than atmospheric pressure, it is required to prevent the atmosphere in the processing chamber from excessively changing when the state in the processing chamber at a pressure lower than atmospheric pressure returns to the atmospheric pressure state. Because particles caused by the excessive variation in the processing chamber must be prevented from being raised and so forth. Therefore, a very small amount of N.sub.2 gas must be supplied to the processing chamber, so that there are problems in that it takes a lot of time and the treating capacity is lowered. However, there is no concrete means for solving these problems in the present circumstances.